Kinetic modeling and experimental study of photocatalytic process using graphene oxide/TiO2 composites. A case for wastewater treatment under sunlight

• Published in: Reaction kinetics, mechanisms and catalysis mechanisms and catalysis, 2021-08, Vol.133 (2), p.1141-1162
• Main Authors: Deflaoui, Ourida, Boudjemaa, Amel, Sabrina, Beldjoudi, Hayoun, Bahdja, Bourouina, Mustapha, Bourouina-Bacha, Saliha
• Format: Article
• Language: English
• Subjects: Catalysis; Chemistry; Chemistry and Materials Science; Industrial Chemistry/Chemical Engineering; Physical Chemistry
• ISSN: 1878-5190; 1878-5204
• DOI: 10.1007/s11144-021-02022-8

Graphene oxide (GO) synthesised by the Hummers method and modified with TiO 2 (xGO/TiO 2 with x = 2, 5, 10, 15 and 30 wt%) is used to improve the photocatalytic reactivity of TiO 2 for the dye removal. The synthesised samples were characterised by XRD, SEM/EDS, BET surface area, RDs, FTIR and EIS. Under sun irradiation, the photocatalysts exhibited efficient photoreactivity. The efficiency of the dye removal reaction increases, after 10 min of solar irradiation, from 14 to 81%upon increasing the % GO from 0 to 30%. The 30GO/TiO 2 composites exhibit better photoactivity under sunlight irradiation compared to the other composites. Thus, after 10 min of irradiation, the MO removal efficiency with the 30GO/TiO 2 photocatalyst reaches 84% of its maximum value (96%). In contrast, with TiO 2 alone, the maximum yield of 81% can only be achieved after 60 min. The modification of the catalyst with GO made it possible to decrease the reaction time necessary to reach the steady-state. Both classical and fractal-like kinetic models applied to photodegradation data showed that the Weibull model is the best fit (RMSE, ARE, R 2 and t 0.5 ). Compared to pure TiO 2 , the 30GO/TiO 2 catalyst shortens the degradation time by half; the photodegradation by xGO/TiO 2 shows a decrease in mass transfer resistance inside a winding channel on the surface and in the fluid film surrounding the catalyst particles. This led to an enhancement in the mass transfer coefficient and intraparticle diffusivity on 30GO/TiO 2 catalyst of about 19 and 13 times compared to the pure TiO 2 .